The present invention relates to a flame retardant resin composition having a high degree of flame retardant property. More particularly the present invention relates to a non-halogenated flame retardant resin composition improved in working environment and safety, reducing the generation of phosphoric acid and excellent in electric characteristics.
The polyester such as a polybutylene terephthalate, etc., has excellent mechanical characteristics, heat resistance, chemical resistance, etc., and is widely used as molded articles for uses in an electric/electronic field, automobile field, etc.
For the molded articles used in these fields, the flame retardant properties are required in many cases. Nowadays, resin compositions using mainly a halogenated compound and an antimony compound as a flame retardant and a flame retardant assistant for imparting the flame retardant property thereto, are generally used.
However, since in the case of using a resin composition containing a halogenated flame retardant as a molded article constituting an electric appliance, sometimes a decomposition product thereof may corrode a metal part which is another element constituting the electric appliance, a non-halogenated flame retardant resin composition has been required. Also, since some halogenated flame retardants cause issues in environmental effects, the non-halogenated flame retardant resin composition is further required.
As the non-halogenated flame retardant, there are phosphorus compounds. As a representative organic phosphorus compound, a low molecular weight phosphate such as triphenylphosphate (TPP), has been frequently used so far. However, since the polyester such as the polybutylene terephthalate, requires a relatively high processing temperature, there were problems of a bleeding and insufficient heat resistance in the case of blending the low molecular weight phosphate.
In the Japanese unexamined patent publication 7-126498 (Unexamined publication on May 16, 1995, Applied on Nov. 8, 1993 as the Japanese patent application 5-278015), a non-halogenated flame retardant for the polyester resin obtained by melting for reacting a polyester-based resin, an epoxy compound having 2 or more epoxy groups in its molecule, a phenolic resin and/or one or more kinds of non-halogenated flame retardant compounds selected from phosphorus-, nitrogen- and boron-based compounds having a functional group capable of reacting with the epoxy group, was disclosed. And in the Japanese unexamined patent publication 7-278267 (Unexamined publication on Oct. 24, 1995, Applied on Apr. 7, 1994 as the Japanese patent application 6-69728), a flame retardant polyester-based resin composition obtained by blending 5 to 50 parts weight above non-halogenated flame retardant with 100 parts weight of a polyester, was disclosed. The above non-halogenated flame retardant is characterized in using an epoxy compound having 2 or more epoxy groups in molecule thereof.
In the Japanese unexamined patent publication 8-188717 (Unexamined publication on Jul. 23, 1996, Applied on Jan. 6, 1995 as the Japanese patent application 7-785), a flame retardant resin composition consisting of a thermoplastic resin such as a polystyrene and a polyester, a phosphorus compound such as a phosphate and a phosphite, and a phenolaralkyl resin such as a reaction product of a phenolic resin (for example; cresol) with an aralkylhalide (for example; xcex1,xcex1-dichloro-p-xylene), was disclosed.
In the Japanese unexamined patent publication 8-208884 (Unexamined publication on Aug. 13, 1996, Applied on Jan. 30, 1995 as the Japanese patent application 7-12825), a flame retardant resin composition consisting of a thermoplastic resin such as a polystyrene and a polyester, a phosphorus compound such as a phosphate and a phosphite, and a phenolic resin prepared from a phenol substituted at the ortho- or para-position, was disclosed.
While, red phosphorus among the phosphorus compounds, is known to exhibit an excellent flame retardant property even by adding a small amount. As the flame retardants using the red phosphorus, the following examples can be cited.
In the Journal of Flame Retardant Chemistry, volume 7, 69-76, 1980, it was disclosed that a polystyrene is made of flame retardant by red phosphorus and a phenolic resin.
In the Plastic Engineering, Nov., 29-31, 1993, it was disclosed that a polybutylene terephtahlate is made of flame retardant by red phosphorus and a phenolic resin.
In the Japanese patent publication 2-37370 (Unexamined patent publication 58-108248 on Jul. 28, 1983, Applied on Dec. 19, 1981 as the Japanese patent application 56-205812), a flame retardant polyester resin composition composed of a thermoplastic polyester having a softening point of 150xc2x0 C. or higher such as a polyethylene terephthalate of 99 to 34 parts weight, red phosphorus coated with a thermosetting resin of 1 to 25 parts weight and a reinforcing filler of 10 to 55 parts weight, was disclosed.
A technology of adding a metal oxide for the purpose of inactivating red phosphorus, was disclosed in the Japanese unexamined patent publication 51-42746 (Unexamined publication on Apr. 12, 1976, Applied on Oct. 9, 1974 as the Japanese patent application 49-115670), the Japanese unexamined patent publication 51-150553 (Unexamined publication on Dec. 24, 1976, Applied on Jul. 9, 1976 as the Japanese patent application 51-67544), etc.
The object of the present invention is to provide a non-halogenated flame retardant resin composition having a high flame retardant property, improved in working environment and safety, also reducing the generation of phosphoric acid which affects electric characteristics thereof and excellent in electric characteristics.
Another object of the present invention is to provide a resin composition for electric/electronic parts consisting of a non-halogenated resin composition having a high flame retardant property and excellent in electric characteristics, and also electric/electronic parts composed thereof.
Further objectives and advantages of the present invention will be clarified by the following explanation.
The present invention comprises the following constitution.
1. A flame retardant resin composition comprising (A) a thermoplastic aromatic polyester of 100 parts weight, (B) a coated red phosphorus powder composed of essentially spherical red phosphorus, having a cured resin coating, directly obtained by a conversion treatment method of yellow phosphorus, not requiring the pulverization and without having crushed surfaces of 1 to 15 parts weight and (C) an aromatic polyearbonate of 5 to 150 parts weight.
2. A flame retardant resin composition according to paragraph 1, wherein (D) at least one kind of a compound selected from a group consisting of titanium oxide, aluminum oxide and molybdenum sulfide is further contained in a range of 0.05 to 5 parts weight based on 100 parts weight of (A) the thermoplastic aromatic polyester.
3. A flame retardant resin composition according to paragraph 2, wherein a generated amount of phosphine after heating the composition at a temperature of 120xc2x0 C. for 24 hours is not more than 5xc3x9710xe2x88x925 g based on 1 g of red phosphorus contained in the composition, and also the generated amount of phosphoric acid by maintaining the composition under a humid and heat condition at a temperature of 121xc2x0 C., at a humidity of 100% RH and under a pressure of 2.1 atm., is not more than 3xc3x9710xe2x88x924 g based on 1 g of the red phosphorus contained in the composition.
4. A flame retardant resin composition according to paragraph 1, wherein an inorganic filler is further contained in a range of 5 to 150 parts weight based on 100 parts weight of (A) the thermoplastic aromatic polyester.
5. A flame retardant resin composition according to paragraph 1, wherein a fluorine resin is further contained in a range of 0.01 to 10 parts weight based on 100 parts weight of (A) the thermoplastic aromatic polyester.
6. A flame retardant resin composition according to paragraph 1, wherein (B) the coated red phosphorus powder and (C) the aromatic polycarbonate are melted and kneaded beforehand.
The present invention is explained in detail as follows.
 less than  less than Thermoplastic Aromatic Polyester greater than  greater than 
The thermoplastic aromatic polyester (A) is a polyester consisting of an aromatic dicarboxylic acid as a main dicarboxylic acid component and an aliphatic diol having a carbon number of 2 to 10 as a main diol component. It contains preferably 80 mole % or more, more preferably 90 mole % or more of the aromatic dicarboxylic acid component based on the total dicarboxylic acid components, and also contains preferably 80 mole % or more, more preferably 90 mole % or more of the aliphatic diol component having the carbon number of 2 to 10 based on the total diol components.
As the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, methyl terephthalate, methyl isophthalate, and 2,6-naphthalene dicarboxylic acid can be cited. They can be used either by one kind, or by two or more kinds simultaneously.
As the dicarboxylic acid component which can be used as a copolymerization component with the aromatic dicarboxylic acid, for example, an aliphatic or an alicyclic dicarboxylic acid such as adipic acid, sebacic acid, decane dicarboxylic acid, azelaic acid, dodecane dicarboxylic acid, cyclohexane dicarboxylic acid, etc., can be cited.
As the aliphatic diol having the carbon number of 2 to 10, for example an aliphatic diol such as ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, etc., and an alicyclic diol such as 1,4-cyclohexane dimethanol, etc., can be cited. These aliphatic diols and alicyclic diols can be used either by one kind or by two or more kinds simultaneously. As the diol component which can be used as the copolymerization component with the aliphatic diols having the carbon number of 2 to 10, for example, p,pxe2x80x2-dihydroxyethoxybisphenol A and a polyoxyethylene glycol can be cited.
Among them, as the thermoplastic aromatic polyester (A), the thermoplastic aromatic polyester composed of an ester unit in which the main dicarboxylic acid component is at least one dicarboxylic acid selected from group consisting of terephthalic acid and 2,6-naphthalene dicarboxylic acid, and the main diol component is at least one kind of diol selected from a group of ethylene glycol, trimethylene glycol and tetramethylene glycol, is preferable.
Especially, a polyester composed of a main recurring unit consisting of ethylene terephthalate, trimethylene terephthalate, tetramethylene terephthalate or tetramethylene-2,6-naphthalene dicarboxylate, is preferable. Also, a polyester elastomer consisting of these recurring unit as a main recurring unit of a hard segment thereof, can be used.
As the above polyester elastomer, an elastomer having tetramethylene terephthalate or tetramethylene-2,6-naphthalene dicarboxylate as a main recurring unit of its hard segment, is preferable. The polyester elastomer is constituted by a soft segment and the above hard segment, and as the soft segment, for example, a polyester elastomer composed of a dicarboxylic acid component consisting of one or more kinds selected from a group consisting of terephthalic acid, isophthalic acid, sebacic acid and adipic acid, and a diol component composed of one or more kinds selected from a group consisting of a long chain diol having carbon number of 5 to 10 and H(OCH2CH2)iOH (i=2-5), and also having a melting point of 100xc2x0 C. or lower, or being amorphous, or a polycaprolactone can be used.
Further, the main component means a component occupying 80 mole % or more, preferably 90 mole % or more of the total dicarboxylic acid components or the total diol components, and the main recurring unit means a recurring unit occupying 80 mole % or more, preferably 90 mole % or more of the total recurring units.
The thermoplastic aromatic polyester (A) has an intrinsic viscosity measured at 35xc2x0 C. in ortho-chlorophenol, of preferably 0.5 to 1.4 dl/g, more preferably 0.6 to 1.2 dl/g. The intrinsic viscosity of less than 0.5 is not preferable since the mechanical strength of the obtained composition is reduced, and the viscosity exceeding 1.4, is also not preferable, since the flowing property, etc., of the obtained composition are reduced.
 less than  less than Coated Red Phosphorus Powder greater than  greater than 
In the present invention, a coated red phosphorus powder (B), consisting essentially of a spherical red phosphorus having a cured resin coating, not requiring a pulverization, directly obtained from a yellow phosphorus conversion treatment method and without having crushed surfaces, is used.
If red phosphorus without having the coating is used, there is a risk of an ignition and a generation of phosphine caused by a high temperature, a mechanical shock, etc.
The coated red phosphorus powder (B) is essentially a spherical-shaped red phosphorus without having crushed surfaces, and obtained by the conversion treating method of yellow phosphorus. By using such essentially spherical red phosphorus, the surfaces thereof are extremely stabilized, the stability of the red phosphorus is increased and the stability of the composition is improved. On the other hand, in the case of using a red phosphorus other than the above essentially spherical red phosphorus, i.e., a red phosphorus obtained as a lump-shaped material by heat-treating yellow phosphorus in a reaction vessel, so-called a conversion pot, for several days and then crushing in a crushing process, there are following problems. That is, since many active points are formed on the surface of the red phosphorus by the crushing, the red phosphorus is liable to react with oxygen or a water molecule and becomes a cause of the ignition and the generation of phosphine and oxide.
As the method for producing the essentially spherical red phosphorus of the coated red phosphorus powder (B), the following method is cited. That is, yellow phosphorus is heated at a temperature in the vicinity of the boiling point thereof in a hermetically closed vessel substituted with an inert gas to initiate a conversion reaction to red phosphorus. And then, the reaction is stopped when the conversion rate or the particle diameter attains a desired level, and the unconverted yellow phosphorus is distilled off By this method, an amorphous red phosphorus composed of fine essentially spherical-shaped particles or associates thereof, totally not requiring a pulverization, is obtained. The conversion rate and the particle diameter of the red phosphorus can be adjusted by a reaction time and a reaction temperature. The preferable reaction temperature is 250 to 350xc2x0 C. and the preferable conversion rate is 60% or less.
The cured resin coating on the coated red phosphorus powder (B) consists preferably of at least one kind of the cured resin selected from a group of a phenolic resin, an epoxy resin, an unsaturated polyester resin, a melamine resin, a urea resin and an aniline resin.
The coated red phosphorus powder (B) is preferably further contains by dispersing at least one kind of inorganic compound selected from a group consisting of aluminum hydroxide, magnesium hydroxide, zinc hydroxide and titanium hydroxide in the cured resin coating.
These inorganic compounds can be further contained under the above cured resin coating by making a contact with the red phosphorus. That is, under the cured resin coating of the coated red phosphorus powder (B), a coating consisting of at least one kind of the inorganic compound selected from a group consisting of aluminum hydroxide, magnesium hydroxide, zinc hydroxide and titanium hydroxide, and making a contact with the red phosphorus, is allowed to be present.
The mean particle diameter of the coated red phosphorus powder (B), is preferably in a range of 5 to 40 g m, more preferably in the, range of 25 to 35 xcexcm. If the mean particle diameter is less than 5 xcexcm, it is not preferable in a view of a dispersion uniformity, and if it exceeds 40 xcexcm, it is also not preferable since the mechanical characteristics and flame retardant property are reduced.
The coated red phosphorus powder (B) is blended so as to become in a range of 1 to 15 parts weight based on the thermoplastic aromatic polyester (A). If the blended amount is less than 1 part weight, the flame retardant property becomes insufficient, and if it exceeds 15 parts weight, the mechanical characteristics of the molded articles obtained from the flame retardant resin composition is reduced.
The coated red phosphorus powder (B) is preferably used as master pellets prepared previously by melting and kneading with the aromatic polycarbonate (C). As the aromatic polycarbonate (C), an aromatic polycarbonate having a viscosity-averaged molecular weight of 20,000 to 25,000, is preferable. If the viscosity-averaged molecular weight is less than 20,000, the flame retardant property is reduced, and if it exceeds 25,000, it is not preferable since the flowing property is reduced to reduce its molding property.
It is possible to obtain a resin composition capable of obtaining a molded article excellent in mechanical property by using the coated red phosphorus powder (B) as master pellets prepared in advance by melting and kneading with the aromatic polycarbonate (C) in making the molded articles. Since the safety is improved, it is desirable to use the above red phosphorus as the master pellets.
By blending the master pellets prepared by mixing and kneading the coated red phosphorus powder (B) with the aromatic polycarbonate (C) in advance, with the thermoplastic aromatic polyester (A), the flame retardant property of the composition is markedly improved in comparison with the case of preparing master pellets of the coated red phosphorus powder (B) with a thermoplastic resin other than the aromatic polycarbonate and blending the obtained master pellets with the thermoplastic aromatic polyester (A) together with the aromatic polycarbonate.
The content of the coated red phosphorus powder (B) in the master pellets, is preferably 10 to 15 weight % based on the total weight of the master pellets. If the content is less than 10 weight %, it is not preferable since the amount of the master pellets to be added, is increased since the efficiency of the flame retardant is relatively reduced, and if the content exceeds 15 weight %, it is also not preferable since it is difficult to prepare the master pellets and also the safety is reduced.
 less than  less than Aromatic Polycarbonate greater than  greater than 
The aromatic polycarbonate (C) is usually obtained by reacting a divalent phenol with a carbonate precursor by a solution method or a melting method.
As the divalent phenol, for example, 2,2-bis(4-hydroxyphenyl)propane (hereinafter may be abbreviated as bisphenol A), 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfone, etc., are cited. A bis(4-hydroxyphenyl)alkane is preferable, and among them bisphenol A is especially preferable. The divalent phenol can be either used singly or by mixing 2 or more kinds of them.
As the carbonate precursor, for example, a carbonyl halide, a carbonate or a haloformate can be cited. As a representative example, phosgene, diphenyl carbonate, a dihaloformate of a divalent phenol and their mixtures are cited. In the production of the aromatic polycarbonate, a suitable molecular weight adjusting agent, branching agent, catalyst, etc., can be used.
The aromatic polycarbonate (C) having 20,000 to 25,000 molecular weight expressed by a viscosity-averaged molecular weight, is preferable. If the molecular weight is less than 20,000, the mechanical strength is reduced and also the flame retardant property is reduced, and if it exceeds 25,000, then the flowing property, etc., are reduced.
The aromatic polycarbonate (C) is blended so as to be in a range of 5 to 150 parts weight, based on the thermoplastic aromatic polyester (A) of 100 parts weight. If the amount is less than 5 parts weight, the flame retardant property is insufficient and if it exceeds 150 parts weight, the mechanical characteristics of the obtained molded article are reduced.
 less than  less than Titanium Oxide, Aluminum Oxide and Molybdenum Sulfide greater than  greater than 
It is preferable for the flame retardant resin composition in the present invention to contain at least one kind of compound (D) selected from a group consisting of titanium oxide, aluminum oxide and molybdenum sulfide. By blending the above component (hereinafter may be called as the (D) component), the essentially spherical red phosphorus in the composition is markedly stabilized and the amount of phosphine generation can be widely reduced.
Such effect as the stabilization of the essentially spherical red phosphorus and the reduction of the phosphine generation can be achieved by adding the titanium oxide, aluminum oxide, molybdenum sulfide or copper oxide, but in the case of blending copper oxide, it is not preferable since copper oxide reacts with the essentially spherical red phosphorus to form phosphoric acid to damage the electric characteristic thereof.
The adding amount of the above mentioned (D) component is preferably 0.05 to 5 parts weight based on the thermoplastic aromatic polyester (A) of 100 parts weight. If the amount is less than 0.05 parts weight, it is not preferable since the stabilizing effect for red phosphorus is small and if it exceeds 5 parts weight, it is also not preferable since the mechanical characteristics of the molded article obtained from the resin composition are reduced.
By blending the above (D) component with the thermoplastic aromatic polyester (A), the coated red phosphorus powder (B) and the aromatic polycarbonate (C) in the above amount, it is possible to obtain a flame retardant resin composition exhibiting the phosphine generating amount after heating at 120xc2x0 C. for 24 hour of 5xc3x9710xe2x88x925 g or less based on 1 g of red phosphorus contained in the flame retardant resin composition, and the phosphoric acid generating amount under a humid heat condition at 121xc2x0 C. temperature, at 100% RH and under 2.1 atm. of 3xc3x9710xe2x88x924 or less based on 1 g of red phosphorus contained in the flame retardant resin composition. In this case, since the stability of the essentially spherical red phosphorus is increased, and also the increase of the phosphoric acid production does not occur, bad effects to electric characteristics are extremely small and a resin composition equipped with good electric characteristics can be obtained.
 less than  less than Additive greater than  greater than 
It is possible for the flame retardant resin composition in the present invention to further contain an inorganic filler in a range, not harming the object of the present invention.
As the inorganic filler, for example, a particle state or an amorphous inorganic filler such as calcium carbonate, titanium oxide, a feldspar-based mineral, a clay, a white carbon, a carbon black, glass beads, a silica, etc., a scaly inorganic filler such as a kaolin clay and a talc, and a fibrous inorganic filler such as a glass fiber, a wollastonite, potassium titanate, aluminum borate, a carbon fiber, an aramid fiber, etc., can be cited. When the inorganic filler is contained, it is preferable to contain the same in a range of 5 to 150 parts weight based on the thermoplastic aromatic polyester (A) of 100 parts weight.
The flame retardant resin composition in the present invention can also contain a flame retardant property-modifying agent. As the flame retardant property-modifying agent, a fluorine resin is preferable, and as the fluorine resin, a polytetrafluoroethylene is cited as an example. In the case of containing the fluorine resin, it is preferable to contain 0.01 to 10 parts weight of the same based on the thermoplastic aromatic polyester (A) of 100 parts weight.
The flame retardant resin composition in the present invention can contain an additive such as an antioxidant, a heat stabilizing agent, an ultraviolet rays-absorbing agent, a lubricant, a nucleating agent, a releasing agent, a pigment, an impact resistance-improving agent such as various elastomers, etc.
The fire retarding resin composition in the present invention can also contain the oxide or hydroxide of zinc, aluminum, magnesium and titanium as a stabilizer of red phosphorus.
 less than  less than Production Method greater than  greater than 
The flame retardant resin composition in the present invention can be produced by a method of melting and kneading master pellets of the coated red phosphorus powder (B) with the aromatic polycarbonate (C), the thermoplastic aromatic polyester (A), and the inorganic filler and the other additive as necessary simultaneously by using, for example, an extruder.
The coated red phosphorus powder (B) and the aromatic polycarbonate (C) are preferably melted and kneaded in advance. By using thus obtained master pellets of the coated red phosphorus powder (B) with the aromatic polycarbonate (C), it is possible to obtain the flame retardant resin composition, wherein the generated amount of phosphine after heating at 120xc2x0 C. for 24 hours is 5xc3x9710xe2x88x925 g or less based on 1 g of red phosphorus contained in the composition, and the produced amount of phosphoric acid under a humid heat condition at 121xc2x0 C., at 100% RH and under 2.1 atm is, 3xc3x9710xe2x88x924 g or less based on 1 g of red phosphorus contained in the composition.
The inorganic filler and the other additives may be melted and kneaded in advance with the thermoplastic polyester (A) or the aromatic polycarbonate (C).
The resin composition obtained by melting and kneading in the extruder, is usually cut as a pellet shape by a pelletizer, and then can be molded to obtain a molded article.
As the method for molding, an injection molding and a blow molding can be exemplified.
The flame retardant composition in the present invention is suitable as the flame retardant resin composition for electric/electronic parts, and suitably used as molded parts used in the electric/electronic uses such as a home electric appliance, an OA instrument, etc., by molding as the electric/electronic parts.
Also, the flame retardant resin composition in the present invention can be used in automobile uses. More concretely, for example, it can be used as a switch part, a motor part, an ignition coil case, a coil bobbin, a connector, a relay case and a fuse case.